What is the legal test for the purpose of obtaining an undertaking in a sexual assault case?

It may be scarcely necessary to say that this undertaking, understood as I agree with my learned brothers in this court and in the court below in interpreting it, is sufficient to demand from the applicant the uberrima fides which is insisted on in one of the reasons of appeal. That the defendants, in framing the undertaking in this form, went as far as was required for their protection is shewn by the case of Roe v. Bradshaw, L.R. 1 Ex. 106, where it was held that when one swears to the best of his knowledge and belief, his statement imports that he is entitled to entertain the belief he expresses.